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Gonioscopy

Dr. Reshma Peter discusses gonioscopy, a technique that allows visualization of the anterior chamber angle using contact lenses. It enables classification of glaucomas by assessing if the angle is open or closed. The document provides a historical overview of gonioscopy and describes the various methods, lenses, and principles of both direct and indirect gonioscopy. Key anatomical structures of the anterior chamber angle are also outlined.

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Dr. Reshma Peter GONIOSCOPY
INTRODUCTION Gonioscopy allows visualization of the anterior chamber angle by using direct or indirect contact lenses to overcome the Total Internal Reflection  Enables glaucomas to be classified by assessing whether the angle is open or closed  Various Pathologies involving angle structures can be observed
HISTORICAL ASPECTS  Trantas (1907) • 1st visualized the anterior chamber angle in a patient with keratoglobus by indenting the limbus • coined the term gonioscopy.  Salzmann (1914) • Established that visualization of the angle was impossible without optical instrumentation due to phemomenon of Total internal reflection • Thus introduced the goniolens  Koeppe (1919) • designed an improved steeper lens. •  Troncoso • developed gonioscope for magnification and illumination of the angle.  Goldmann (1938) • introduced the gonioprism  Barkan • established the use of gonioscopy in the management of glaucoma
Anatomy Of the Angle
ANGLE STRUCTURES
PRINCIPLES AND OPTICS • Critical angle for the cornea-air interface is approximately 46 degrees. •Total internal reflection prevents direct visualization of ang le in nearly all eyes. •The incident angle of light- reflected from angle is greater than the critical angle at the cornea–air interface.
L i < L r light rays are refracted at the contact l ens-air interface light rays are reflected by a mirror light rays leave the lens at nearly right angles at the contact lens-air interface Total internal reflection is overcome by eliminate the cornea-air interface by Goniolenses in DIRECT method contact lenses –-to examine the anatomy of the angle Gonioprisms/mirror and viscous coupling solution or tears in INDIRECT method As the index of refraction of a contact lens approaches that of the corne a, there is minimal refraction at the interface of these two media, which eliminates the optical effect of the front corneal surface. Thus light rays from the anterior chamber angle enter the contact lens a nd are then made to pass through the new contact lens-air interface
METHODS • Three primary methods: • Indirect gonioscopy: Using mirrors,the angle is examined with reflected light • Indentation (dynamic) gonioscopy • Direct gonioscopy: look directly at the angle with lenses.
GONIOPRISMS(Indirect) GONIOLENSES(Direct) Requiring coupling agents Not requiring coupling agents 1.Goldmann single mirror gonioprism 2.Goldmann 2 mirror gonioprism 3.Goldmann 3 mirror gonioprism 4.Allen Thorpe gonioprism 1.Zeiss 4- mirror Gonioprism 2.Posner Gonioprism 3.Sussman lens 4.Tokel Gonioprism 5.Ritch Trabeculoplasty laser lens 1.Koeppe Goniolens 2.Huskins Barkans lens 3.Thorpe Goniolens 4.Swan Jacob ‘s lens 5.Richardson Shaffer’s Goniolens 6.Worth goniolens 7.Sieback goniolens
GONIOPRISMS Requiring coupling agents 1.Goldmann single mirror gonioprism Prototype diagnostic gonioprism • Mirror inclined at 62 degrees from plano front surface • Needs to be rotated 3times to examine the whole angle • Mirror Height -12 mm • Central well diameter -12 mm • Posterior Radius of curvature -7.38 mm
2.Goldmann two mirror gonioprism • Both mirrors inclined at 62 degrees • Needs to be rotated once to examine whole angle 3.Goldmann three mirror gonioprism
1.Gonioscopy mirror: • Smallest • Dome shaped upper border • Inclination of 59 degrees Broad area of contact with cornea (12 mm) may artificially close the angle under pressure 2.Equatorial mirror: • Largest • Oblong shaped • Inclined at 67 degrees • Examine Pars plana of ciliary body Posterior pole to the equator 3.Peripheral mirror: • Intermediate size • Square shaped • Inclined at 73 degrees • Examine from equator to ora serrata
4.Allen Thorpe gonioprism • 4 prisms instead of mirrors • Allows examination of whole angle without rotating the prisms • Suspended by a frame
Advantages of Goldmann gonioprisms • Easy to use • Excellent view • Peripheral retina can be seen • Stabilizes the globe Can be used in Argon Laser trabeculoplasty
Disadvantages of Goldmann gonioprisms • Only 1 mirror for gonio-has to be rotated by 360 degrees • Cannot be used for indentation • In case of 3 mirror lens, broad area of contact with cornea may cause artefactual closure of angle Curvature of lens > cornea Coupling material required Blurs vision and fundus Field charting ,direct and indirect ophthalmosc opy cant be done immediately after use
GONIOPRISMS Not requiring coupling agents 1.Zeiss 4- mirror Gonioprism • 4 identical mirrors angled at 64 degrees • On an UNGER HOLDER • Small area of contact with the cornea (9mm) Indentation gonioscopy can be performed
Zeiss 4- mirror Gonioprism ADVANTAGES DISADVANTAGES • Easy to perform • All 4 quadrants visible at sa me time • Rotation of 11 degrees covers area between the mirrors • Indentation gonio • Coupling material not required, thus fundus viewing and photography possible • Difficult to master • Does not stabilise the globe • May open the angle artefactually If pressure is applied
2.Posner Gonioprism • Similar to Zeiss • Made of plastic instead of glass • Has a fixed handle
3.Sussman lens Similar to Zeiss but has no handle 4.Tokel Gonioprism • Single mirror lens • Broader viewing area than Goldmann single mirror lens • Convex anterior face that provides slight magnification • For delivery of Laser to angle
5.Ritch Trabeculoplasty laser lens • 2 mirrors tilted at 59degrees to see inferior angle • 2 mirrors at 64 degrees to view the superior angle • A convex button in front of a 59 degree mirror and a 64 degree mirror for extra magnification and laser treatment
GONIOLENSES Koeppe lens • Prototype diagnostic lens • Available in several sizes • Most commonly used lens for diagnostic direct gonio. Huskins Barkan lens • Prototype surgical goniolens • Used for Goniotomy Thorpe Goniolens Surgical and diagnostic lens for operating rooms
Swan jacob’s lens • Surgical goniolens • used in children Richardson Shaffer’s lens Small lens for use in infants Worth goniolens It anchors to the cornea by partial vaccum Sieback goniolens Tiny goniolens which floats on the cornea
DIRECT GONIOSCOPY • Patient in Supine position • 4 %Xylocaine as topical anaesthesia • Saline bridge the gap between lens and cornea • Koeppe lens – 50 D convex lens • External Hand held binocular microscope • External Barker focal illuminator with other hand • Possible simultaneous comparison of both eyes • Image is direct and upright.
TOTAL MAGNIFICATION MAGNIFICATION DUE TO KOEPPE LENS MAGNIFICATION DUE TO MICROSCOPE x 1.5 x 16 X 24
• Offers a panoramic, less magnified view than indirect gonioscopy. • Less likely to exert pressure upon the cornea or limbus, causing errors
Advantages of Direct Gonioscopy  The height of the observer may be changed to look deeper into a narrow angle, whereas the gonioprism is limited by the height of the mirror  Angle becomes deeper in supine position – easier to see angle  Provides a straight-on view of the angle rather than the mirror image given by the indirect lenses.  Panoramic view, so 1 part of angle can be com pared to other
 Goniolens may cause less distortion of the ante rior chamber  Using 2 lenses,both eyes can be simultaneously examined  Possible to vary the angle of visualization more easily. Therefore, a narrow angle can be assessed to see if it is a steep approach to an open angle or a completely closed angle.  Can be used for surgical procedures like gonioto my and goniosynechialysis  Can be used in sedated or anesthetized patient s, as in the examination of children
Disdvantages of Direct Gonioscopy  Inconvenient  Annoying light reflexes from the cornea  Timeconsuming  Benefits of slit lamp not available
INDIRECT GONIOSCOPY PROCEDURE  Dim illumination  Eye anaesthetised with topical agent  Appropriate positioning of the patient at slit lamp
The concave face of Goldmann lens should be filled with a Methyl cellulose coupling fluid before its applied to the eye. Care should be taken to keep air bubbles out of the solution
 Patient is asked to look down  Thumb used to retract the upper eyelid  Lower edge of gonioscope placed on inferior sclera  Gonioscope tipped on to the cornea in 1 smooth maneouvre
Slit lamp gonioscopy • The part that is viewed is 180 degrees away from the mirror that is being used. • Slit lamp beam is focussed on the mirror that shows the angle diametrically opposite to it. • Image is inverted but not laterally reversed • Illumination and height of slitlamp are reduced so that it doesn’t impinge on the pupil and cause pupillary constriction and Artefactual opening of angle.
• With a narrow, short slit beam off axis, the quadrant o f the angle to be assessed is first examined with the f our-mirror lens, with  no pressure on the cornea  the patient looking sufficiently far in the direction of the mirror that the examiner can see as deeply into the angl e as possible. • The inferior portion of the angle is typically the widest and where the trabecular meshwork has the most pigment, thus easiest to identify structures and familiarize with patient ‘s anatomy • Thus most clinicians apply lens so that mirror is at the top of the eye, to allow inferior angle to be examined first. • Then the goniolens is rotated to view other portions of the angle
Illumination methods Diffuse illumination Focal illumination with a broad beam
Focal illumination with a narrow beam
• Using a narrow slit beam at an oblique angle • 2 linear reflections identified from  external surface of cornea and its junction with sclera  Internal surface of cornea • They meet at Schwalbe s line. • Slit of light appears above Schwalbe ‘s line as a 3D parallelepiped of light. • Used for identifying landmarks in patients with  Closed angles  Open angles with no trabecular meshwork pigmentation
Advantages of Indirect Gonioscopy • Easier to learn • Faster to perform, particularly with the Zeiss four-mirror lenses and modified Goldmann-type lenses, because no viscous bridge is required. • Slitlamp provides better optics, variable magnification and illumination • Requires fewer additional instruments and occupies less space than direct gonioscopy. • Gonioprisms with a posterior radius of curvature closer to that of the anterior corneal surface may also reduce Corneal distortion.
• Gonioprisms with taller mirrors facilitate visualization of narrow angles. • The slit beam can create a corneal wedge to help to define the structures of the angle. • Because of its relatively small diameter of corneal contact, the Zeiss four-mirror lens can also be used in compressive gonioscopy. • Indentation gonioscopy can be performed with the Posner or Sussmann lens to distinguish appositional from synechial angle closure. • Magnified stereoscopic view of the optic disc can be obtained
Disadvantages of Indirect Gonioscopy • Limited positioning of light rays • Comparison not possible • Difficult to perform in horizontal meridian • Inverted Mirror image seen – confusing • Excess pressure over the cornea will displace aqueous from the center of the anterior chamber into the periphery,disloc ating the iris posteriorly and falsely opening the anterior ch amber angle. • Posterior pressure may indent the sclera and falsely narrow the angle.
• Goldmann lens requires an optical coupling between the cornea and the lens. ( four-mirror Zeiss lens ,Posner, Sussman have a smaller area of contact and have almost the same radius of curvature as the cornea, which allows the tear film to function as the optical coupling agent.)
Occludable Angles During Gonioscopy in situ (No angle structures are visible) Optical or Apparent closure Appositional closure Synechial Closure Look for abnormalities in angle Manipulative gonioscopy Indentation gonioscopy
To look for angle abnormalities • Increase the room and slit lamp illumination • Allow light to impinge on pupil • Thereby opening up angle
Manipulative/Dynamic Gonioscopy  In eyes with a steep iris configuration  manipulate Goldmann lens to visualise over a steep iris (OVER HILL VIEW)  Ask patient to look in direction of mirror or  Move mirror towards angle being viewed
Indentation Gonioscopy  performed in a completely darkened room usi ng the smallest square of light for a slit beam to avoid stimulating the pupillary light reflex.  Effective with Zeiss , Posner, Sussman ,Allen Thorpe lens whose areas of contact are small er than the cornea(no coupling media)  Goldmann and Koeppe have larger areas of c ontact and may make the angle shallower wit h indentation
• Bending of the cornea results in mechanical rotation of the li mbus, giving more direct view of the angle • Permits examiner to look deep into angle recess for iridodialysis, foreign bodies or cyclodialysis clefts • By deliberately varying the amount of pressure applied to the cornea- observe the effects on angle width. • Measures extent of angle closure • Useful in convex iris configuration and Plateau configur ation - (retain convex profile) • Performed in all cases • The ability to visualize angle structures by indentation-redu ced in the presence of elevated intraocular pressure.
• Differentiate form appositional or s ynechial closure
Corneal edema  In patients with corneal edema ,  topical anaesthesia followed by Glycerin  Short lived effect  In goniotomy, visualisation of edematous corneal epithelium after it is scraped away after wetting the cornea with 70 % ethyl alcohol
INDICATIONS • Shallow Ant chamber • High IOP • Pigment dispersion • Pseudoexfoliation • History of Blunt trauma • NVI • Ocular Inflammation • Compromised Vascular system of Reti na
CONTRAINDICATIONS • Perforated Globe • Hyphaema • Herpes Simplex • Epidemic Keratoconjunctivitis • Epithelial basement dystrophies
Interpretation of gonioscopy findings
Interpretation of gonioscopy findings PUPIL • looking at the pupil for rapid orientation. • Anterior lens surface can be observed for focal opacifications (glaukomflecken) and for poster ior synechiae. • View the white dandruff-like flecks of exfoliative pigment at the posterior edge of the pupil, whi ch is typical of exfoliative syndrome. • Iridodonesis is present to a small degree in so me deep-chambered Normal eyes and is easily observed if of a pathologic degree.
IRIS • Configuration of the peripheral iris contour of the iris, noting its flatness -deep anterior chamber convexity (or even bowing) -a shallow anterior cham ber peripheral concavity -high myopia or signs of pigment dispersion • Site of iris insertion in reference to structures within the angle recess  at the level of the upper trabecular meshwork and S chwalbe’s line  at the level of the filtering trabecular meshwork  just below the scleral spur  below the spur in the ciliary body  deep posteriorly in the ciliary band.
Anteriorly inserting irides, at the level of the spur or TM -more common among Asians and in patients with hyperopia. • Angulation between the iris insertion and the slo pe of the inner cornea in the angle, in approxima te steps of 10°. This systematic assessment of angle anatomy is the basis of the most detailed gonioscopic gradin systems. • Abnormalities such as neovascularization, hypop lasia,atrophy, and polycoria should be noted.
CILIARY BODY BAND • The ciliary body band appears as a densely pigmented band just behind Scleral Spur • dull-brown to slate grey band • Width depends on position of iris insertion (Narrower -- hyperopes wider – myopes ) • If abnormally deep and not symmetrical with the other eye –  angle recession  Cyclodialysis  unilateral high myopia
SCLERAL SPUR • Site of attachment of longitudinal muscle of Ciliary Body • Appears as narrow, dense, shiny white band • Imp. Landmark (relatively consistent appearance) • Blood in the Schlemm ‘s canal –lies anterior to spur
SCHLEMM’S CANAL • Lies deep to posterior trabeculum • Normally not visible • Seen if blood is present in Increased Episcleral V enous Pressure – Gonio lens - pressure – Carotid-cavernous fistula – Sturge Weber syndrome – Venous Compression – Hypotony
TRABECULAR MESHWORK • Pigmented band anterior to Scleral Spur • Width - 600µm • Gonioscopic appearance - Ground glass, irregularly roughened due to large openings of uveal meshwork • 2 parts  Anterior - non functional part (White)  Posterior - functional pigmented part (greyish blue) primary site of aqueous outflow • has no pigment at birth, but with age, color develops, from f aint tan to dark brown, depending on the degree of pigment dispersion in the anterior chamber. • distribution of pigment may be homogeneous in some and ir regular in others.
SCHWALBE’S LINE • Collagen condensation of descement membrane between T.M. and endothelium • Thin translucent line or ridge like structure • The corneal wedge-identifying the schwalbe’s line • Using a narrow slit beam at an oblique angle • 2 linear reflections identified from  external surface of cornea and its junction with sclera  Internal surface of cornea Parallelopiped beam of light is seen , apex of which corresponds to Schwalbe s line.
IRIS PROCESSES • Small extensions from anterior surface of iris to level of Scleral Spur but sometimes as far anteriorly as schwalbe’s line • Lacy fenestrated • Underlying angle structures visible between strands • Seen in 1/3 rd of normal eyes –not pathological • Prominent in myopes / brown eyes • Common in nasal Quadrant
Iris Processes  Lacy fenestrated  Underlying angle stru ctures visible between strands  Tend to follow recess PAS Iridocorneal adhesions  Short ,stout projections  May obscure the scleral spur  Bridge the recess  Tether iris to angle and interfere with posterior motion of the iris during Indentation
Blood Vessels in the Angle • Two types Circumferential vessels • found at the base of the iris or in the angle recess. • Appearance- of an undulating “sea serpent” • with segments of blood vessel visible against the ciliary body, punctuate d by areas where the vessel dips posteriorly and out of view • never seen attached to the angle anterior to the scleral spur. Radial iris vessels within the iris stroma - mimic corkscrews Normal angle vessel • Broad • Appears in short segment • Not extend anterior to S.S pur • Do not arborize in the T. M Pathological angle vessels • Fine • Cross the scleral spur • Branch, arborize in T.M.
Sampaolesi line • Line of irregular pigmentation deposit anterior to Schwalbe’s line • sampaolesi’s line can be mistaken for trabecular m eshwork in narrow angle Sampaolesi’s Line Salt , pepper Dark granular Discontinuous Pigmentation T.M Brown sugar Fine Continuous
ARTIFACT AND AVOIDANCE • Use thin slit lamp •  illumination • Goldman type lens - avoid indentation- cause ar tificially narrowing of angle • Zeiss - avoid pressure  artificial widening of the angle
INTERPRETATION OF GONIOSCOPIC FINDINGS • Several grading systems- describe the width of the anterior chamber angle a nd its potential for angle closure. • Shaffer, Scheie, and Spaeth-three most commonly used systems.
ANGLE GRADING SYSTEMS FOR GONIOSCOPY
SHAFFER’S GRADING SL to CB SL to SS SL to TM SL only
• Spaeth also graded posterior pigmented meshwork in the 12 o’clock angle on a scale Of 0 to 4+ and this grade is often assigned separately at the end of the gonioscopic description.
RECORDING GONIOSCOPIC FINDINGS
CLINICAL USES • Aid in diagnosis of type of glaucoma  Open Vs closed angle  Narrow angle  Cause of sec. Glaucoma • Decision of iridotomy • Pre-Operative examination • Post operative evaluation  Ostium  Cleft goniotomy / cyclodialysis  Iridotomy • Assess K-F ring (Wilson) • Therapeutic  Goniotomy  Laser procedure (ALT)  Chamber deepening procedure  Acute angle closure –break synechia by indentati on
• NEOVASCULARIZATION OF ANGLE: • Vessels- erratic course and/or extend anteriorly past the level of the scleral spur. • Vascular retinal abnormalities such as  diabetic retinopathy  retinal venous or arterial occlusions  ocular ischemic syndrome. • accompanied by PAS • Heterochromic cyclitis-  vessels are fewer, finer  not accompanied by peripheral anterior synechiae. • Healed cataract incision PATHOLOGICAL FINDINGS
PLATEAU IRIS  Unusual form of primary angle closure , not by pupillary block.  Angle closed by prominent last roll of iris and abnormal approach of iris to angle  A patent PI or iridotomy must be present for the diagnosis  Ciliary processes – abnormally forward  On indentation , central iris is pushed back but peripheral iris held up by ciliary processes
PAS IN ANTERIOR UVEITIS
Pseudoexfoliation
Pigment dispersion syndrome
Traumatic Iridodialysis
ANGLE RECESSION
Iris Bombe
Iris Coloboma
Posterior Embryotoxon
Axenfeld anomaly
Malignant melanoma
Angle closure-post uveitis
Foreign body
Aniridia
Disinfection • With all lenses the manufacturer's instructions for disinfection should be followed to prevent damage to the lens. • It is important to carefully remove the disinfectant from the contact s urface before the next use, because alcohol and hydrogen peroxide e ach cause transient corneal defects. • Most lenses can be gas-sterilized and some glass lenses can be autoc laved. • Most common method is inverting the contact lens and wiping the s urface with an alcohol sponge. • lens can be inverted and the concave contact area filled with a solution of 1: 10 household bleach, which is left for 5 min and then rinsed off with water. Adenovirus type 8 soaking the lens for 5 to 15 minutes in diluted sodium hypochlo rite (1:10 household bleach), 3% hydrogen peroxide, or 70% is opropyl alcohol, or by wiping with alcohol, hydrogen peroxide, i odophor (povidone-iodine), or 1:1000 Merthiolate HSV Type1 swabbing the lens with 70% isopropyl alcohol HBV Ten minutes of continuous rinsing in running tap water HIV-1 Wipe with 3% hydrogen peroxide or 70% isopropyl alcohol swab s
REFERENCES 1.SHIELD ‘S TEXTBOOK OF GLAUCOMA 6th e , by R RAND AL LINGHAM 2. BECKER –SHAFFER S DIAGNOSIS AND THERAPY OF GLAU COMAS 3.THE GLAUCOMA BOOK , A PRACTICAL EVIDENCE BASED A PPROACH TO PATIENT CARE by Paul N. Schacknow 4. HANDBOOK OF GLAUCOMA by Augusto Azuara- Blanco 5.THEORY AND PRACTICE OF OPTICS AND REFRACTION by A.K. Khurana 6.COLOUR ATLAS OF GONIOSCOPY by Wallace L.M. Alward

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Gonioscopy

  • 1.
  • 2.
    INTRODUCTION Gonioscopy allows visualization of theanterior chamber angle by using direct or indirect contact lenses to overcome the Total Internal Reflection  Enables glaucomas to be classified by assessing whether the angle is open or closed  Various Pathologies involving angle structures can be observed
  • 3.
    HISTORICAL ASPECTS  Trantas(1907) • 1st visualized the anterior chamber angle in a patient with keratoglobus by indenting the limbus • coined the term gonioscopy.  Salzmann (1914) • Established that visualization of the angle was impossible without optical instrumentation due to phemomenon of Total internal reflection • Thus introduced the goniolens  Koeppe (1919) • designed an improved steeper lens. •  Troncoso • developed gonioscope for magnification and illumination of the angle.  Goldmann (1938) • introduced the gonioprism  Barkan • established the use of gonioscopy in the management of glaucoma
  • 4.
  • 8.
  • 9.
    PRINCIPLES AND OPTICS •Critical angle for the cornea-air interface is approximately 46 degrees. •Total internal reflection prevents direct visualization of ang le in nearly all eyes. •The incident angle of light- reflected from angle is greater than the critical angle at the cornea–air interface.
  • 10.
    L i <L r light rays are refracted at the contact l ens-air interface light rays are reflected by a mirror light rays leave the lens at nearly right angles at the contact lens-air interface Total internal reflection is overcome by eliminate the cornea-air interface by Goniolenses in DIRECT method contact lenses –-to examine the anatomy of the angle Gonioprisms/mirror and viscous coupling solution or tears in INDIRECT method As the index of refraction of a contact lens approaches that of the corne a, there is minimal refraction at the interface of these two media, which eliminates the optical effect of the front corneal surface. Thus light rays from the anterior chamber angle enter the contact lens a nd are then made to pass through the new contact lens-air interface
  • 11.
    METHODS • Three primarymethods: • Indirect gonioscopy: Using mirrors,the angle is examined with reflected light • Indentation (dynamic) gonioscopy • Direct gonioscopy: look directly at the angle with lenses.
  • 12.
    GONIOPRISMS(Indirect) GONIOLENSES(Direct) Requiring coupling agentsNot requiring coupling agents 1.Goldmann single mirror gonioprism 2.Goldmann 2 mirror gonioprism 3.Goldmann 3 mirror gonioprism 4.Allen Thorpe gonioprism 1.Zeiss 4- mirror Gonioprism 2.Posner Gonioprism 3.Sussman lens 4.Tokel Gonioprism 5.Ritch Trabeculoplasty laser lens 1.Koeppe Goniolens 2.Huskins Barkans lens 3.Thorpe Goniolens 4.Swan Jacob ‘s lens 5.Richardson Shaffer’s Goniolens 6.Worth goniolens 7.Sieback goniolens
  • 13.
    GONIOPRISMS Requiring coupling agents 1.Goldmannsingle mirror gonioprism Prototype diagnostic gonioprism • Mirror inclined at 62 degrees from plano front surface • Needs to be rotated 3times to examine the whole angle • Mirror Height -12 mm • Central well diameter -12 mm • Posterior Radius of curvature -7.38 mm
  • 14.
    2.Goldmann two mirrorgonioprism • Both mirrors inclined at 62 degrees • Needs to be rotated once to examine whole angle 3.Goldmann three mirror gonioprism
  • 15.
    1.Gonioscopy mirror: • Smallest •Dome shaped upper border • Inclination of 59 degrees Broad area of contact with cornea (12 mm) may artificially close the angle under pressure 2.Equatorial mirror: • Largest • Oblong shaped • Inclined at 67 degrees • Examine Pars plana of ciliary body Posterior pole to the equator 3.Peripheral mirror: • Intermediate size • Square shaped • Inclined at 73 degrees • Examine from equator to ora serrata
  • 16.
    4.Allen Thorpe gonioprism •4 prisms instead of mirrors • Allows examination of whole angle without rotating the prisms • Suspended by a frame
  • 17.
    Advantages of Goldmanngonioprisms • Easy to use • Excellent view • Peripheral retina can be seen • Stabilizes the globe Can be used in Argon Laser trabeculoplasty
  • 18.
    Disadvantages of Goldmanngonioprisms • Only 1 mirror for gonio-has to be rotated by 360 degrees • Cannot be used for indentation • In case of 3 mirror lens, broad area of contact with cornea may cause artefactual closure of angle Curvature of lens > cornea Coupling material required Blurs vision and fundus Field charting ,direct and indirect ophthalmosc opy cant be done immediately after use
  • 19.
    GONIOPRISMS Not requiring couplingagents 1.Zeiss 4- mirror Gonioprism • 4 identical mirrors angled at 64 degrees • On an UNGER HOLDER • Small area of contact with the cornea (9mm) Indentation gonioscopy can be performed
  • 20.
    Zeiss 4- mirrorGonioprism ADVANTAGES DISADVANTAGES • Easy to perform • All 4 quadrants visible at sa me time • Rotation of 11 degrees covers area between the mirrors • Indentation gonio • Coupling material not required, thus fundus viewing and photography possible • Difficult to master • Does not stabilise the globe • May open the angle artefactually If pressure is applied
  • 21.
    2.Posner Gonioprism • Similarto Zeiss • Made of plastic instead of glass • Has a fixed handle
  • 22.
    3.Sussman lens Similar toZeiss but has no handle 4.Tokel Gonioprism • Single mirror lens • Broader viewing area than Goldmann single mirror lens • Convex anterior face that provides slight magnification • For delivery of Laser to angle
  • 23.
    5.Ritch Trabeculoplasty laserlens • 2 mirrors tilted at 59degrees to see inferior angle • 2 mirrors at 64 degrees to view the superior angle • A convex button in front of a 59 degree mirror and a 64 degree mirror for extra magnification and laser treatment
  • 24.
    GONIOLENSES Koeppe lens • Prototypediagnostic lens • Available in several sizes • Most commonly used lens for diagnostic direct gonio. Huskins Barkan lens • Prototype surgical goniolens • Used for Goniotomy Thorpe Goniolens Surgical and diagnostic lens for operating rooms
  • 25.
    Swan jacob’s lens • Surgicalgoniolens • used in children Richardson Shaffer’s lens Small lens for use in infants Worth goniolens It anchors to the cornea by partial vaccum Sieback goniolens Tiny goniolens which floats on the cornea
  • 26.
    DIRECT GONIOSCOPY • Patientin Supine position • 4 %Xylocaine as topical anaesthesia • Saline bridge the gap between lens and cornea • Koeppe lens – 50 D convex lens • External Hand held binocular microscope • External Barker focal illuminator with other hand • Possible simultaneous comparison of both eyes • Image is direct and upright.
  • 27.
    TOTAL MAGNIFICATION MAGNIFICATION DUE TOKOEPPE LENS MAGNIFICATION DUE TO MICROSCOPE x 1.5 x 16 X 24
  • 28.
    • Offers apanoramic, less magnified view than indirect gonioscopy. • Less likely to exert pressure upon the cornea or limbus, causing errors
  • 29.
    Advantages of Direct Gonioscopy The height of the observer may be changed to look deeper into a narrow angle, whereas the gonioprism is limited by the height of the mirror  Angle becomes deeper in supine position – easier to see angle  Provides a straight-on view of the angle rather than the mirror image given by the indirect lenses.  Panoramic view, so 1 part of angle can be com pared to other
  • 30.
     Goniolens maycause less distortion of the ante rior chamber  Using 2 lenses,both eyes can be simultaneously examined  Possible to vary the angle of visualization more easily. Therefore, a narrow angle can be assessed to see if it is a steep approach to an open angle or a completely closed angle.  Can be used for surgical procedures like gonioto my and goniosynechialysis  Can be used in sedated or anesthetized patient s, as in the examination of children
  • 31.
    Disdvantages of Direct Gonioscopy Inconvenient  Annoying light reflexes from the cornea  Timeconsuming  Benefits of slit lamp not available
  • 32.
    INDIRECT GONIOSCOPY PROCEDURE  Dimillumination  Eye anaesthetised with topical agent  Appropriate positioning of the patient at slit lamp
  • 33.
    The concave faceof Goldmann lens should be filled with a Methyl cellulose coupling fluid before its applied to the eye. Care should be taken to keep air bubbles out of the solution
  • 34.
     Patient isasked to look down  Thumb used to retract the upper eyelid  Lower edge of gonioscope placed on inferior sclera  Gonioscope tipped on to the cornea in 1 smooth maneouvre
  • 36.
    Slit lamp gonioscopy •The part that is viewed is 180 degrees away from the mirror that is being used. • Slit lamp beam is focussed on the mirror that shows the angle diametrically opposite to it. • Image is inverted but not laterally reversed • Illumination and height of slitlamp are reduced so that it doesn’t impinge on the pupil and cause pupillary constriction and Artefactual opening of angle.
  • 37.
    • With anarrow, short slit beam off axis, the quadrant o f the angle to be assessed is first examined with the f our-mirror lens, with  no pressure on the cornea  the patient looking sufficiently far in the direction of the mirror that the examiner can see as deeply into the angl e as possible. • The inferior portion of the angle is typically the widest and where the trabecular meshwork has the most pigment, thus easiest to identify structures and familiarize with patient ‘s anatomy • Thus most clinicians apply lens so that mirror is at the top of the eye, to allow inferior angle to be examined first. • Then the goniolens is rotated to view other portions of the angle
  • 38.
    Illumination methods Diffuse illuminationFocal illumination with a broad beam
  • 39.
  • 40.
    • Using anarrow slit beam at an oblique angle • 2 linear reflections identified from  external surface of cornea and its junction with sclera  Internal surface of cornea • They meet at Schwalbe s line. • Slit of light appears above Schwalbe ‘s line as a 3D parallelepiped of light. • Used for identifying landmarks in patients with  Closed angles  Open angles with no trabecular meshwork pigmentation
  • 42.
    Advantages of Indirect Gonioscopy •Easier to learn • Faster to perform, particularly with the Zeiss four-mirror lenses and modified Goldmann-type lenses, because no viscous bridge is required. • Slitlamp provides better optics, variable magnification and illumination • Requires fewer additional instruments and occupies less space than direct gonioscopy. • Gonioprisms with a posterior radius of curvature closer to that of the anterior corneal surface may also reduce Corneal distortion.
  • 43.
    • Gonioprisms withtaller mirrors facilitate visualization of narrow angles. • The slit beam can create a corneal wedge to help to define the structures of the angle. • Because of its relatively small diameter of corneal contact, the Zeiss four-mirror lens can also be used in compressive gonioscopy. • Indentation gonioscopy can be performed with the Posner or Sussmann lens to distinguish appositional from synechial angle closure. • Magnified stereoscopic view of the optic disc can be obtained
  • 44.
    Disadvantages of Indirect Gonioscopy •Limited positioning of light rays • Comparison not possible • Difficult to perform in horizontal meridian • Inverted Mirror image seen – confusing • Excess pressure over the cornea will displace aqueous from the center of the anterior chamber into the periphery,disloc ating the iris posteriorly and falsely opening the anterior ch amber angle. • Posterior pressure may indent the sclera and falsely narrow the angle.
  • 45.
    • Goldmann lensrequires an optical coupling between the cornea and the lens. ( four-mirror Zeiss lens ,Posner, Sussman have a smaller area of contact and have almost the same radius of curvature as the cornea, which allows the tear film to function as the optical coupling agent.)
  • 46.
    Occludable Angles During Gonioscopyin situ (No angle structures are visible) Optical or Apparent closure Appositional closure Synechial Closure Look for abnormalities in angle Manipulative gonioscopy Indentation gonioscopy
  • 47.
    To look forangle abnormalities • Increase the room and slit lamp illumination • Allow light to impinge on pupil • Thereby opening up angle
  • 48.
    Manipulative/Dynamic Gonioscopy  Ineyes with a steep iris configuration  manipulate Goldmann lens to visualise over a steep iris (OVER HILL VIEW)  Ask patient to look in direction of mirror or  Move mirror towards angle being viewed
  • 49.
    Indentation Gonioscopy  performedin a completely darkened room usi ng the smallest square of light for a slit beam to avoid stimulating the pupillary light reflex.  Effective with Zeiss , Posner, Sussman ,Allen Thorpe lens whose areas of contact are small er than the cornea(no coupling media)  Goldmann and Koeppe have larger areas of c ontact and may make the angle shallower wit h indentation
  • 51.
    • Bending ofthe cornea results in mechanical rotation of the li mbus, giving more direct view of the angle • Permits examiner to look deep into angle recess for iridodialysis, foreign bodies or cyclodialysis clefts • By deliberately varying the amount of pressure applied to the cornea- observe the effects on angle width. • Measures extent of angle closure • Useful in convex iris configuration and Plateau configur ation - (retain convex profile) • Performed in all cases • The ability to visualize angle structures by indentation-redu ced in the presence of elevated intraocular pressure.
  • 52.
    • Differentiate formappositional or s ynechial closure
  • 54.
    Corneal edema  Inpatients with corneal edema ,  topical anaesthesia followed by Glycerin  Short lived effect  In goniotomy, visualisation of edematous corneal epithelium after it is scraped away after wetting the cornea with 70 % ethyl alcohol
  • 55.
    INDICATIONS • Shallow Antchamber • High IOP • Pigment dispersion • Pseudoexfoliation • History of Blunt trauma • NVI • Ocular Inflammation • Compromised Vascular system of Reti na
  • 56.
    CONTRAINDICATIONS • Perforated Globe •Hyphaema • Herpes Simplex • Epidemic Keratoconjunctivitis • Epithelial basement dystrophies
  • 57.
  • 58.
    Interpretation of gonioscopy findings PUPIL •looking at the pupil for rapid orientation. • Anterior lens surface can be observed for focal opacifications (glaukomflecken) and for poster ior synechiae. • View the white dandruff-like flecks of exfoliative pigment at the posterior edge of the pupil, whi ch is typical of exfoliative syndrome. • Iridodonesis is present to a small degree in so me deep-chambered Normal eyes and is easily observed if of a pathologic degree.
  • 59.
    IRIS • Configuration ofthe peripheral iris contour of the iris, noting its flatness -deep anterior chamber convexity (or even bowing) -a shallow anterior cham ber peripheral concavity -high myopia or signs of pigment dispersion • Site of iris insertion in reference to structures within the angle recess  at the level of the upper trabecular meshwork and S chwalbe’s line  at the level of the filtering trabecular meshwork  just below the scleral spur  below the spur in the ciliary body  deep posteriorly in the ciliary band.
  • 60.
    Anteriorly inserting irides,at the level of the spur or TM -more common among Asians and in patients with hyperopia. • Angulation between the iris insertion and the slo pe of the inner cornea in the angle, in approxima te steps of 10°. This systematic assessment of angle anatomy is the basis of the most detailed gonioscopic gradin systems. • Abnormalities such as neovascularization, hypop lasia,atrophy, and polycoria should be noted.
  • 62.
    CILIARY BODY BAND •The ciliary body band appears as a densely pigmented band just behind Scleral Spur • dull-brown to slate grey band • Width depends on position of iris insertion (Narrower -- hyperopes wider – myopes ) • If abnormally deep and not symmetrical with the other eye –  angle recession  Cyclodialysis  unilateral high myopia
  • 63.
    SCLERAL SPUR • Siteof attachment of longitudinal muscle of Ciliary Body • Appears as narrow, dense, shiny white band • Imp. Landmark (relatively consistent appearance) • Blood in the Schlemm ‘s canal –lies anterior to spur
  • 64.
    SCHLEMM’S CANAL • Liesdeep to posterior trabeculum • Normally not visible • Seen if blood is present in Increased Episcleral V enous Pressure – Gonio lens - pressure – Carotid-cavernous fistula – Sturge Weber syndrome – Venous Compression – Hypotony
  • 65.
    TRABECULAR MESHWORK • Pigmentedband anterior to Scleral Spur • Width - 600µm • Gonioscopic appearance - Ground glass, irregularly roughened due to large openings of uveal meshwork • 2 parts  Anterior - non functional part (White)  Posterior - functional pigmented part (greyish blue) primary site of aqueous outflow • has no pigment at birth, but with age, color develops, from f aint tan to dark brown, depending on the degree of pigment dispersion in the anterior chamber. • distribution of pigment may be homogeneous in some and ir regular in others.
  • 66.
    SCHWALBE’S LINE • Collagencondensation of descement membrane between T.M. and endothelium • Thin translucent line or ridge like structure • The corneal wedge-identifying the schwalbe’s line • Using a narrow slit beam at an oblique angle • 2 linear reflections identified from  external surface of cornea and its junction with sclera  Internal surface of cornea Parallelopiped beam of light is seen , apex of which corresponds to Schwalbe s line.
  • 67.
    IRIS PROCESSES • Smallextensions from anterior surface of iris to level of Scleral Spur but sometimes as far anteriorly as schwalbe’s line • Lacy fenestrated • Underlying angle structures visible between strands • Seen in 1/3 rd of normal eyes –not pathological • Prominent in myopes / brown eyes • Common in nasal Quadrant
  • 68.
    Iris Processes  Lacyfenestrated  Underlying angle stru ctures visible between strands  Tend to follow recess PAS Iridocorneal adhesions  Short ,stout projections  May obscure the scleral spur  Bridge the recess  Tether iris to angle and interfere with posterior motion of the iris during Indentation
  • 69.
    Blood Vessels inthe Angle • Two types Circumferential vessels • found at the base of the iris or in the angle recess. • Appearance- of an undulating “sea serpent” • with segments of blood vessel visible against the ciliary body, punctuate d by areas where the vessel dips posteriorly and out of view • never seen attached to the angle anterior to the scleral spur. Radial iris vessels within the iris stroma - mimic corkscrews Normal angle vessel • Broad • Appears in short segment • Not extend anterior to S.S pur • Do not arborize in the T. M Pathological angle vessels • Fine • Cross the scleral spur • Branch, arborize in T.M.
  • 70.
    Sampaolesi line • Lineof irregular pigmentation deposit anterior to Schwalbe’s line • sampaolesi’s line can be mistaken for trabecular m eshwork in narrow angle Sampaolesi’s Line Salt , pepper Dark granular Discontinuous Pigmentation T.M Brown sugar Fine Continuous
  • 71.
    ARTIFACT AND AVOIDANCE •Use thin slit lamp •  illumination • Goldman type lens - avoid indentation- cause ar tificially narrowing of angle • Zeiss - avoid pressure  artificial widening of the angle
  • 72.
    INTERPRETATION OF GONIOSCOPIC FINDINGS •Several grading systems- describe the width of the anterior chamber angle a nd its potential for angle closure. • Shaffer, Scheie, and Spaeth-three most commonly used systems.
  • 73.
  • 74.
    SHAFFER’S GRADING SL toCB SL to SS SL to TM SL only
  • 76.
    • Spaeth alsograded posterior pigmented meshwork in the 12 o’clock angle on a scale Of 0 to 4+ and this grade is often assigned separately at the end of the gonioscopic description.
  • 77.
  • 78.
    CLINICAL USES • Aidin diagnosis of type of glaucoma  Open Vs closed angle  Narrow angle  Cause of sec. Glaucoma • Decision of iridotomy • Pre-Operative examination • Post operative evaluation  Ostium  Cleft goniotomy / cyclodialysis  Iridotomy • Assess K-F ring (Wilson) • Therapeutic  Goniotomy  Laser procedure (ALT)  Chamber deepening procedure  Acute angle closure –break synechia by indentati on
  • 79.
    • NEOVASCULARIZATION OFANGLE: • Vessels- erratic course and/or extend anteriorly past the level of the scleral spur. • Vascular retinal abnormalities such as  diabetic retinopathy  retinal venous or arterial occlusions  ocular ischemic syndrome. • accompanied by PAS • Heterochromic cyclitis-  vessels are fewer, finer  not accompanied by peripheral anterior synechiae. • Healed cataract incision PATHOLOGICAL FINDINGS
  • 80.
    PLATEAU IRIS  Unusualform of primary angle closure , not by pupillary block.  Angle closed by prominent last roll of iris and abnormal approach of iris to angle  A patent PI or iridotomy must be present for the diagnosis  Ciliary processes – abnormally forward  On indentation , central iris is pushed back but peripheral iris held up by ciliary processes
  • 81.
  • 82.
  • 83.
  • 84.
  • 85.
  • 86.
  • 87.
  • 88.
  • 89.
  • 91.
  • 92.
  • 93.
  • 94.
  • 95.
    Disinfection • With alllenses the manufacturer's instructions for disinfection should be followed to prevent damage to the lens. • It is important to carefully remove the disinfectant from the contact s urface before the next use, because alcohol and hydrogen peroxide e ach cause transient corneal defects. • Most lenses can be gas-sterilized and some glass lenses can be autoc laved. • Most common method is inverting the contact lens and wiping the s urface with an alcohol sponge. • lens can be inverted and the concave contact area filled with a solution of 1: 10 household bleach, which is left for 5 min and then rinsed off with water. Adenovirus type 8 soaking the lens for 5 to 15 minutes in diluted sodium hypochlo rite (1:10 household bleach), 3% hydrogen peroxide, or 70% is opropyl alcohol, or by wiping with alcohol, hydrogen peroxide, i odophor (povidone-iodine), or 1:1000 Merthiolate HSV Type1 swabbing the lens with 70% isopropyl alcohol HBV Ten minutes of continuous rinsing in running tap water HIV-1 Wipe with 3% hydrogen peroxide or 70% isopropyl alcohol swab s
  • 96.
    REFERENCES 1.SHIELD ‘S TEXTBOOKOF GLAUCOMA 6th e , by R RAND AL LINGHAM 2. BECKER –SHAFFER S DIAGNOSIS AND THERAPY OF GLAU COMAS 3.THE GLAUCOMA BOOK , A PRACTICAL EVIDENCE BASED A PPROACH TO PATIENT CARE by Paul N. Schacknow 4. HANDBOOK OF GLAUCOMA by Augusto Azuara- Blanco 5.THEORY AND PRACTICE OF OPTICS AND REFRACTION by A.K. Khurana 6.COLOUR ATLAS OF GONIOSCOPY by Wallace L.M. Alward

Editor's Notes

  • #5 limbus is the transition zone between the cornea and the sclera. On the inner surface of the limbus is an indentation; the scleral sulcus, which has a sharp posterior margin- the scleral spur; and a sloping anterior wall that extends to the peripheral cornea
  • #6 A sieve-like structure, the trabecular meshwork, bridges the scleral sulcus and converts it into a tube, called the Schlemm canal. Where the meshwork inserts into the peripheral cornea, a ridge is created, known as the Schwalbe line. The Schlemm canal is connected by intrascleral channels to the episcleral veins. The trabecular meshwork, Schlemm canal, and the intrascleral channels make up the main route of aqueous humor outflow
  • #7 ciliary body attaches to the scleral spur and creates a potential space, the supraciliary space, between itself and the sclera. On cross section, the ciliary body has the shape of a right triangle, and the ciliary processes (the actual site of aqueous humor production) occupy the innermost and anterior-most portion of this structure in the region called the pars plicata (or corona ciliaris). The posterior portion of the ciliary body, called the pars plana (or orbicularis ciliaris), has a flatter inner surface and joins the choroid at the ora serrata. The pars plicata region is also composed of smooth muscle, which serves the important functions of accommodation and uveoscleral outflow.
  • #8 The iris inserts into the anterior side of the ciliary body, leaving a variable width of the latter structure visible between the root of the iris and the scleral spur, referred to as the ciliary body band. The lens is suspended from the ciliary body by zonules and separates the vitreous posteriorly from the aqueous humor anteriorly. The iris separates the aqueous humor compartment into a posterior and an anterior chamber, and the angle formed by the iris and the cornea is called the anterior chamber angle
  • #9 FROM ANTERIOR TO POSTERIOR
  • #10 When light passes from a denser medium with a greater index of refraction to one with a lesser index Light is transmitted when i< r i= critical angle when r is 90 degrees. When i exceeds the critical angle, r >i , the light is reflected back into the first medium.
  • #11   In direct gonioscopy, the anterior curve of the contact lens—the goniolens—is such that the critical angle is not reached, and the light rays are refracted at the contact lens-air interface   In indirect gonioscopy, the --leave the lens at nearly a right angle to the contact lens-air interface  
  • #51 Indentation pressure over the cornea will displace aqueous from the center of the anterior chamber into the periphery towards the angles ,pushes the iris posteriorly and falsely opening the anterior chamber angle
  • #54 Angle opens up on Indentation but TM is seen as patchy areas of pigmentation between which we can see patchy areas of PAS Iris is gradually encroaching on to tm
  • #75 Based on the angle between iris and Trabecular meshwork
  • #76 estimated angle between a line tangential to the trabecular meshwork and a line tangential to the surface of the iris about one-third of the way from the periphery “f” to denote a flat configuration “c”to describe the “concave” iris, “b” to describe the forwardly “bowed” iris “p” for a plateau iris configuration.
  • #84 Pigment dispersion throughout the anterior segment
  • #85 Tears in the iris as a result of blunt trauma
  • #86 As a result of very severe blunt trauma – tear in the face of ciliary body , between longitudinal and circular muscles. Increased risk of glaucoma Wide ciliary band and deep AC
  • #87 Iris bombe occurs in patients with secluded pupil as aqueous humour trapped in posterior chamber pushes iris forward
  • #89 Axenfeld Reiger syndrome mostly .. Maybe isolated